SQL Server Backup and Restore - Simple Talk

Chapter 1: Basics of Backup and Restore
(Chapters 3 to 8) will focus on database backups (full and differential) and transaction log
backups. However, we do cover file backups in Chapters 9 and 10.
Note that the exact types of backup that can be performed, and to some extent the
restore options that are available, depend on the recovery model in which the database
is operating (SIMPLE, FULL or BULK_LOGGED). We'll be discussing this topic in more
detail shortly, in the Recovery Models section, but for the time being perhaps the most
notable point to remember is that it is not possible to perform transaction log backups
for a database operating in SIMPLE recovery model, and so log backups play no part of a
database RESTORE operation for these databases. Now we'll take a look at each of these
types of backup in a little more detail.
SQL Server database backups
The database backup, which is a backup of your primary data file plus any secondary
database files, is the cornerstone of any enterprise's backup and recovery plan.
Any database that is not using file backups will require a strategy for performing database
backups. Consider, for example, the situation in which a SQL Server database crashes,
perhaps due to a hardware failure, and the live data file is no longer accessible. If no
backups (copies) of this file exist elsewhere, then you will suffer 100% data loss; the
"meltdown" scenario that all DBAs must avoid at all costs.
Let's examine the two types of database backup, full and differential. Each of them
contains the same basic type of information: the system and user data and objects stored
in the database. However, viewed independently, the former contains a more complete
picture of the data than the latter.
29